Method for determining a measured variable of a medium, especially for turbidity measurement

Abstract

Method for determining a measured value of a measured variable of a medium, by means of an optical sensor arrangement, which has at least one transmitter and at least one receiver, comprising the steps as follows: supplying the at least one transmitter with an exciter signal for producing an optical transmitter signal with a transmission signal strength, wherein the transmitter signal is converted by interaction with the medium as a function of the measured variable into a changed transmitter signal; producing a receiver signal from the transformed transmitter signal by means of the at least one receiver and registering a receiver signal strength of the receiver signal; conforming an excitation signal strength of the exciter signal based on the registered receiver signal strength for reaching a predetermined receiver signal strength; and registering the excitation signal strength required for reaching the predetermined receiver signal strength and determining the measured value therefrom.

1 - 8 . (canceled) 
     
     
         9 . A method for determining a measured value of a measured variable of a medium, especially for turbidity measurement in a liquid or gaseous medium, by means of an optical sensor arrangement, which has at least one transmitter and at least one receiver associated with the transmitter, comprising the steps of:
 supplying the at least one transmitter with an exciter signal for producing an optical transmitter signal with a transmission signal strength, wherein the transmitter signal is converted by interaction with the medium as a function of the measured variable into a changed transmitter signal;   producing a receiver signal from the transformed transmitter signal by means of the at least one receiver and registering a receiver signal strength of the receiver signal;   conforming an excitation signal strength of the exciter signal based on the registered receiver signal strength for reaching a predetermined receiver signal strength; and   registering the excitation signal strength required for reaching the predetermined receiver signal strength and determining the measured value therefrom.   
     
     
         10 . The method as claimed in  claim 9 , wherein:
 the exciter signal is controlled as a function of the registered receiver signal strength for reaching a predetermined value of the receiver signal strength.   
     
     
         11 . The method as claimed in  claim 9 , wherein:
 the at least one transmitter includes a light source, especially a light-emitting diode, and the exciter signal is an operating voltage or an operating current of the light source.   
     
     
         12 . The method as claimed in  claim 9 , wherein:
 the at least one receiver includes at least one photoelectric element, especially a photodiode.   
     
     
         13 . The method as claimed in  claim 12 , wherein:
 the receiver signal is a photocurrent dependent on a light intensity received by the photoelectric element or a photovoltage dependent on the light intensity impinging on the photoelectric element.   
     
     
         14 . The method as claimed in  claim 12 , wherein:
 the receiver signal is produced by integration of a photocurrent dependent on a light intensity received by the photoelectric element or a photovoltage dependent on the light intensity impinging on the photoelectric element over a predetermined integration time.   
     
     
         15 . The method as claimed in  claim 9 , wherein:
 the receiver signal is converted by means of an analog/digital converter into a digital receiver signal.   
     
     
         16 . The method as claimed in  claim 15 , wherein:
 for adjusting or controlling the exciter signal, the digital receiver signal is compared with a predetermined signal value, and, based on this comparison, the exciter signal is tuned in such a manner that the receiver signal agrees with the predetermined signal value.